As a preparation for administering a drug to the body for the treatment or prophylaxis of a disease, for example, transdermal absorption type preparations can be mentioned, which can avoid drug metabolism due to the first-pass through the liver and various side effects, and can sustainably administer a drug for a long time. Among those, a patch preparation containing a drug in an adhesive has been developed, since an administration operation is easy and the dose can be strictly controlled.
In general, a patch preparation comprises a support made of a cloth, a plastic film and the like and an adhesive layer containing a drug, which is laminated on the support, and is provided with a release liner laminated on the adhesive layer and in a package made of a resin film and the like.
In recent years, a bulkier adhesive layer is often employed to maintain a large amount of a drug in an adhesive layer. As other characteristic of recent patch preparations, a soft adhesive layer tends to be employed such as an adhesive layer containing a large amount of a liquid component therein and the like, in an attempt to improve a soft feeling on adhesion to the skin, or reduce skin irritation due to detachment of stratum corneum during peeling. For such patch preparations, protrusion of the components of the adhesive layer from the edge of the adhesive patch, i.e., cold flow, poses problems during adhesion to the skin layer. Cold flow occurs depending on the property of the adhesive, and is often developed particularly when the adhesive layer is not crosslinked. In addition, it often occurs when a patch preparation is under a load for a long time, namely, when a patch preparation is contained in a package and stored for a long period and the like. Adverse influences of cold flow include, for example, degraded performance of taking out of a patch preparation from a package, which is caused by adhesion of protruded adhesive layer components to the inside of the package, attachment to clothes, edge lifting and staining of patch preparation during adhesion to the skin, lower effect of adhesive patch having a medicinal effect and the like.
A document working on such problems is, for example, patent document 1. In the cross sectional shape of the patch preparation of patent document 1, at least one part of a lateral end is located on the central part side of the patch preparation than the line segment perpendicularly drawn from a lateral end of a support to a release liner. However, since such a lateral end of an adhesive layer has a large exposed area, when it is soaked in water for a long time such as a bath and the like, a component such as a drug and the like may elute from the exposed lateral end of an adhesive layer of a patch preparation adhered to the skin, thus lowering the efficacy.
In addition, although not a drug-containing patch preparation, patent document 2 discloses a hydrocolloid dressing material having a smaller thickness in the peripheral part than in the central part, since the peripheral part is embossed. This document describes, “when the thickness of the peripheral part is too large, the edge of the peripheral part is easily peeled during application, and when it is too thin, sufficient adhesiveness to the skin surface cannot be ensured and wrinkles are easily developed during application”. However, it does not describe or suggest that a lateral end of an adhesive layer in the peripheral part is located inside the lateral end of the support, nor does it teach the problems of decreased efficacy due to contact with water and the like.